A user-based electronic device for improving convenience of a user is being developed while functions of the electronic device are developed. For example, when a user holds the electronic device horizontally and then holds it vertically, the electronic device performs an automatic screen change (rotation) after sensing velocity, gravity, and the like, thereof and automatically changing (rotating) a screen thereof.
However, because the electronic device ascertains motion of the electronic device itself and changes the screen thereof, a change of angle of the user's face is not considered in the above-described automatic screen change method of the electronic device. For example, when the user lies down and watches the screen of the electronic device, with respect to gravity acting on the electronic device, the electronic device displays an upper surface of a screen on an opposite side of a side on which gravity acts and displays a lower surface of the screen on the side on which gravity acts. That is, because the user lies down, the user watches the screen of the electronic device at the user's right or left side at 90 degrees to the electronic device. Accordingly, the user may not watch the screen of the electronic device straight.
Therefore, a user-based electronic device for automatically ascertaining motion of a user instead of motion of the electronic device itself is needed.